Expired with IRB (2/2/2019).

A person's blood type is defined by the types of sugars they express on their red blood cells, with antibodies being made to non-self sugars and excluding blood cells expressing these sugars (the basis of blood transfusion reactions). These same sugars can be expressed by commensal bacteria in our gut lumens. The investigators hypothesize that a person's antibodies to non-self sugars also attach to and exclude non-self sugar-expressing bacteria in our guts. Supporting our hypothesis, a person's blood type correlates with the overall composition of their gut flora. Because these sugars are also used by certain pathogens to initiate infection, this information could directly inform our understanding of host susceptibility to various infectious organisms.

A member of the study staff will collect a small volume of blood sample through a finger prick and 2-3 milliliters of saliva from you. Using these samples, we will determine your blood type (defined by your expression of specific sugars on your red blood cells) and your expression pattern of these sugars in body secretions (e.g., saliva). You will provide us with a fecal sample collected the day of your appointment. The fecal sample should be collected in a pre-provided collection container and should be collected within 12 hours of drop-off. Using your fecal sample, we will determine the types of bacteria present in your normal gut flora and whether they express the same sugars expressed on your blood cells. Tests will be done only for research purposes and will not be evaluated or used to diagnose or treat any of your medical problems. Sample collection may need to be repeated if required for your medical care in the future.

Inclusion Criteria:

• healthy,
• adult

Exclusion Criteria:

• younger than 18,
• older than 60,
• pregnant

Healthy adults